.TH std::ctype::tolower,std::ctype::do_tolower 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::ctype::tolower,std::ctype::do_tolower \- std::ctype::tolower,std::ctype::do_tolower

.SH Synopsis
   Defined in header <locale>
   public:                                                                \fB(1)\fP
   CharT tolower( CharT c ) const;
   public:                                                                \fB(2)\fP
   const CharT* tolower( CharT* beg, const CharT* end ) const;
   protected:                                                             \fB(3)\fP
   virtual CharT do_tolower( CharT c ) const;
   protected:                                                             \fB(4)\fP
   virtual const CharT* do_tolower( CharT* beg, const CharT* end ) const;

   1,2) Public member function, calls the protected virtual member function do_tolower
   of the most derived class.
   3) Converts the character c to lower case if a lower case form is defined by this
   locale.
   4) For every character in the character array [beg, end), for which a lower case
   form exists, replaces the character with that lower case form.

.SH Parameters

   c   - character to convert
   beg - pointer to the first character in an array of characters to convert
   end - one past the end pointer for the array of characters to convert

.SH Return value

   1,3) Lower case character or c if no lower case form is listed by this locale.
   2,4) end

.SH Notes

   Only 1:1 character mapping can be performed by this function, e.g. the Greek
   uppercase letter 'Σ' has two lowercase forms, depending on the position in a word:
   'σ' and 'ς'. A call to do_tolower cannot be used to obtain the correct lowercase
   form in this case.

.SH Example


// Run this code

 #include <iostream>
 #include <locale>

 void try_lower(const std::ctype<wchar_t>& f, wchar_t c)
 {
     wchar_t up = f.tolower(c);
     if (up != c)
         std::wcout << "Lower case form of \\'" << c << "' is " << up << '\\n';
     else
         std::wcout << '\\'' << c << "' has no lower case form\\n";
 }

 int main()
 {
     std::locale::global(std::locale("en_US.utf8"));
     std::wcout.imbue(std::locale());
     std::wcout << "In US English UTF-8 locale:\\n";
     auto& f = std::use_facet<std::ctype<wchar_t>>(std::locale());
     try_lower(f, L'Σ');
     try_lower(f, L'Ɛ');
     try_lower(f, L'Ａ');

     std::wstring str = L"HELLo, wORLD!";
     std::wcout << "Lowercase form of the string '" << str << "' is ";
     f.tolower(&str[0], &str[0] + str.size());
     std::wcout << '\\'' << str << "'\\n";
 }

.SH Output:

 In US English UTF-8 locale:
 Lower case form of 'Σ' is σ
 Lower case form of 'Ɛ' is ɛ
 Lower case form of 'Ａ' is ａ
 Lowercase form of the string 'HELLo, wORLD!' is 'hello, world!'

.SH See also

   toupper  invokes do_toupper
            \fI(public member function)\fP
   tolower  converts a character to lowercase
            \fI(function)\fP
   towlower converts a wide character to lowercase
            \fI(function)\fP
